You initially indicated that the softener is calculating water use at almost 2X that which you actually use. As we now know your water source is municipal, it appears you are comparing the softener reading against a municipal meter usually used for billing purposes. As such, the municipal meter should be most accurate as your water bill will be based on that measurement.
As previously stated, verify that the softener settings are appropriate for a turbine meter as the two meter types sense and report flow differently. If the softener is incorrectly programmed to expect information from a paddle wheel meter when a turbine is actually installed, then the softener's water use calculations will indeed be totally incorrect. Likewise, verify that the turbine is measuring the outlet port from the softener, not the inlet port.
These verification's are suggested as a means to establish the reason the softener's meter is reading higher than the billing meter. The billing meter should be higher as it measures all water consumed whereas the softener's meter should only be recording the softened water consumed by the home's occupants, not water utilized for softener regeneration or water which bypasses the softener.
By your comments above, you appear to be surprised by the amount of salt required to operate your new softener and expected you could reduce salt consumption without affecting the amount of water it could soften. Similar to your vehicle consuming fuel when it is operating, the amount of salt needed to regenerate softening capacity is directly related to the amount of capacity that is consumed and needing to be restored. While you had mentioned wasting salt as though consuming it is a waste, in practice, salt is the fuel which is required to operate the softener. Your concern would rightly be best directed at utilizing it efficiently.
Your water contains a significant amount of hardness and at 500 gallons/day, your consumption rate is quite substantial. As it is most unlikely to obtain your water from a source with less hardness, perhaps it is possible to reduce your water consumption requirements by modifying existing practices or by utilizing higher efficiency fixtures and appliances.
How many people reside in your home? With efficient fixtures and appliances, the average US consumption rate is now typically estimated as roughly 60 gallons or less per person per day.